How much does a graphics card cost?

I know the title is very vague, but i don't know much about computers.

I am looking for a Graphics Card that is suitable for playing PC games in decent graphics settings.

I don't know the current specs of my Graphics Card but i know it's really bad.

I tried to play Company of Heroes, a game from 2006, and on the lowest possible graphics settings, and lowered screen resolution, it was still running slow.

So if possible, could anyone give me details of any graphics cards designed specifically for games, or if they are rather expensive, the best graphics card i could get for under £150 ($240)

If it matters (again, i know very little about PCs) i have Vista, a dual processor of 2GHz each, RAM speed is 2GB, under 'Display Adapters' in the Device Manager, it says something about a 'chipset family' if that means anything significant. And finally, the is 32-bit something. Sorry, i can't remember the full name of that.

So if anyone has any advice on what sort of GC to get, or anything else you think needs 'upgrading' let me know.

I have no idea of the price-range of anything, so i could either be being ridiculously high or quite low in saying £150.

I'm buying from the UK by the way, Northern Ireland more specifically.

Whenever i buy whatever it is i need, i will be paying to get it fitted by a professional, or most of it.
However i know that most of the hardware on PCs is quite easily removed and installed, simply involving removing the side cover and changing things. But if changing a Graphics Card involves software updates, or manually doing something whilst logged on to the computer, tell me if you can, then i will have it fitted in a shop. I don't want to try anything myself that i might mess up.

the price of graphics cards vary massively from as little as £25, all the way into the high hundreds of pounds, you want a graphics card to suit you, enough power to do what you want it to, but not to overpay for a more powerful gpu than you will need, if your in the uk aswell browse www.ebuyer.com , www.scan.com , www.aria.com , and have a look at a few typically you will want a gpu with at least 512mb onboard memory but personally i would go for one with 1gb onboard memory either ddr3 or even better ddr5.

You might as well upgrade your ram along the way since most games now a days needs the minimum amount of 2gb for vista/7 computers. Make sure your power supply has enough wattage to support all this though, you don't wanna see your comp smoking during an intense gaming session.